/**
 * Created by h p on 2016/3/31.
 */
import java.util.Scanner;

public class Average {
    public static void main(String[] args){
        Scanner console = new Scanner (System.in);
        double sum  = 0;
        int count = 0;
        while(true){
            int number = console.nextInt();
            if(number == 0){break;}
            sum +=number;
            count ++;
        }
        System.out.printf("平均%.2f%n",sum / count);
    }
}
